import jdk.swing.interop.SwingInterOpUtils;

public class demo1 {
    public static void main(String[] args) {
        Computer.useUSB(new KeyBoard());
        Computer.useUSB(new Mouse());
    }
}
interface USB{
    double USBVERSION=3.0;
    public abstract void startWork();
    public abstract void stopWork();
}
class Computer {
    public static void useUSB(USB usbDevice) {
        usbDevice.startWork();
        usbDevice.stopWork();
    }
}
class KeyBoard implements USB {
    public void startWork() {
        System.out.println("键盘开始工作");
    }
    public void stopWork() {
        System.out.println("键盘停止工作");
    }
}
class Mouse implements  USB {
    public void startWork() {
        System.out.println("鼠标开始工作");
    }
    public void stopWork() {
        System.out.println("鼠标停止工作");
    }
}